Troubleshooting Tip: Partial interface configuration loss after upgrading FortiGate to FortiOS 7.6.4

Description

This article describes an intermittent partial configuration loss condition observed after upgrading a FortiGate to FortiOS 7.6.4.

Scope

FortiOS 7.6.4.

Solution

This issue may occur when the FortiGate is rebooted after the upgrade and the interface configuration is not fully preserved.

The behavior has mainly been observed in production environments where FortiManager automatically performs configuration polling operations.

As a preventive action, create a full configuration backup before performing the upgrade.

Go to Dashboard -> Status -> System Information -> Configuration -> Backup -> Local PC.

Before rebooting the FortiGate after the upgrade, manually change any interface configuration and save the change.

Example CLI change:

config system interface
    edit "port1"
        set description "temporary-save-before-reboot"
    next
end

 
After the configuration is saved, the FortiGate can be rebooted.

The FortiGate may present one or more of the following symptoms.

• Partial configuration loss.

• Interface configuration loss.

• Loss of connectivity after reboot.

 If the issue occurs, compare the current configuration with the backup collected before the upgrade and restore the missing interface   configuration as needed.